Gas turbines are widely used in industrial and commercial operations. A typical gas turbine includes an axial compressor at the front, one or more combustors around the middle, and a turbine at the rear. The compressor includes multiple stages of rotating blades and stationary vanes. Ambient air enters the compressor, and the rotating blades and stationary vanes progressively impart kinetic energy to the working fluid (air) to bring it to a highly energized state. The working fluid exits the compressor and flows to the combustors where it mixes with fuel and ignites to generate combustion gases having a high temperature and pressure. The combustion gases exit the combustors and flow to the turbine where they expand to produce work. The combustion gases exit the turbine as exhaust gases and flow through an exhaust section downstream from the turbine. The exhaust section generally includes an exhaust diffuser having an increasing cross-sectional area. The increasing cross-sectional area of the exhaust diffuser decreases the velocity and increases the static pressure of the exhaust gases, converting the kinetic energy of the exhaust gases into potential energy.
Various factors influence the length and width of the exhaust diffuser. For example, the cross-sectional area of the exhaust diffuser generally determines the maximum energy that may be recovered from the exhaust gases. For a given cross-sectional area at the outlet, a slight increase in the cross-sectional area axially through the exhaust diffuser increases the recovery of potential energy from the exhaust gases, but results in a longer exhaust diffuser. Conversely, a rapid increase in the cross-sectional area axially through the exhaust diffuser results in a shorter exhaust diffuser for the same cross-sectional area at the outlet, but may also allow the exhaust gases to separate from the exhaust diffuser, reducing the recovery of potential energy from the exhaust gases. Therefore, a gas turbine exhaust diffuser that enhances efficiency of the gas turbine in a shorter length would be useful.